1. Field of the Invention.
This invention has relation to a rotary actuator of a type serving as a transducer for controlling the angular position of a damper actuator shaft as a function of variations in fluid pressure within the actuator.
2. Description of the Prior Art.
Damper actuators which serve as linear motors to control the straight line linear positioning of actuator shafts as a function of variations in fluid pressure within the actuator are well known. Such actuators have been sold by Kreuter Manufacturing Company as their Model MCP-1040 and Model MCP-1140 Damper Actuators. To properly install such actuators, however, in such a manner as to use the linear movement of the shaft to control the angular position of a damper shaft rotatably mounted and extending outwardly from an air duct, for example, is labor intensive and time consuming. A special angle bracket must be fastened to the damper actuator and the angle bracket then carefully mounted to the duct wall in fixed relationship to the damper shaft. Next a crank arm had to be loosely installed on the damper shaft before the angle bracket was firmly fixed in position. A number of very carefully positioned sheet metal screws were then used to attach the bracket to the duct work, the crank arm was lined up with the linear damper actuator shaft, the position of the damper blade checked. Only then the crank arm set screws were tightened on the damper shaft. Installations not carefully made resulted in wear on misaligned parts and eventual failure. Any shifting of the actuator mechanisms with respect to the damper, damper shaft and/or duct wall over time can also result in wear and eventual failure.
Other variations of mechanims to convert the linear motion of an actuator shaft to rotary motion of a damper shaft have also included the use of a crank arm mounted on the damper shaft and in some manner or other to the linearly moving actuator shaft. All have required very careful installation, and, over the months and years of operation, many have experienced wear and breakdown of parts due to misalignment of the damper shaft, the crank arm, and the linearly moving actuator shaft.
What was needed before the present invention was a rotary actuator which could be mounted directly with respect to the damper shaft, for example, to reduce very substantially the time needed for installation; and to eliminate forever the possiblity of misalignment of the parts with respect to the damper and the damper shaft.